Stability analysis of collective neutrino oscillations in the supernova accretion phase with realistic energy and angle distributions

TL;DR

This study performs a linear stability analysis of supernova neutrino flavor conversions, incorporating realistic energy and angular distributions, revealing that matter suppression is generally effective, with some exceptions in low-mass supernova models.

Contribution

It extends previous models by including realistic neutrino energy and angle distributions, showing their effects on flavor stability during supernova accretion phases.

Findings

Multi-energy effects have a sub-leading impact on flavor stability.

Realistic forward-peaked angular distributions enhance matter suppression.

Collective flavor conversions are negligible in iron-core supernovae during accretion.

Abstract

We revisit our previous results on the matter suppression of self-induced neutrino flavor conversions during a supernova (SN) accretion phase, performing a linearized stability analysis of the neutrino equations of motion, in the presence of realistic SN density profiles. In our previous numerical study, we used a simplified model based on an isotropic neutrino emission with a single typical energy. Here, we take into account realistic neutrino energy and angle distributions. We find that multi-energy effects have a sub-leading impact in the flavor stability of the SN neutrino fluxes with respect to our previous single-energy results. Conversely, realistic forward-peaked neutrino angular distributions would enhance the matter suppression of the self-induced oscillations with respect to an isotropic neutrino emission. As a result, in our models for iron-core SNe, collective flavor conversions have a negligible impact on the characterization of the observable neutrino signal during the accretion phase. Instead, for a low-mass O-Ne-Mg core SN model, with lower matter density profile and less forward-peaked angular distributions, collective conversions are possible also at early times.